Multi-contact electrical switches



1964 R. A. F. PENSIS 3,143,621

MULTI-CONTACT ELECTRICAL SWITCHES Original Filed Oct. 21, 1958 s Sheets-Sheet 1 76 2 24a I IIH i 26 I .mml, nlllh. F I I H l /8 22a 0 28d\ I L N I I) Aug. 4, ,1964 R. A. F. PENSIS MULTI-CONTACT ELECTRICAL SWITCHES 3 Sheets-Sheet 2 Original Filed Oct. 21, 1958 FIG. 2

1964 R. A. F. PENSIS 3,143,621

MULTI-CONTACT ELECTRICAL SWITCHES v Original Filed Oct. 21, 1958 3 Sheets-Sheet 3 United States Patent O This application is a divisional application of my copending application, Serial No. 768,631, filed October 21, 1958 and now Patent No. 3,014,999.

This invention pertains to electrical switchgear and more particularly to multi-contact electrical switches for on-load tap changing of transformers.

Generally, in such tap changes, a movable support member carries a plurality of contacts coupled to one terminal of the transformer while a fixed support member carries a corresponding plurality of contacts divided into two groups which are coupled via adequate impedances respectively to two successive taps of the transformer. The moving support member is moved with respect to the stationary support member and pairs of contacts are sequentially connected so that the tap may be changed without an interruption of current flow in the load and the portion of the winding between the taps is shunted by the impedances during the passage from one tap to another. The disconnected end of the switch is then displaced to the following tap and the same operation is continued until the required voltage is reached.

Although such switches work satisfactorily in many applications, they often cannot handle the required quantities of current unless they are excessively large. Further because of their complexity and size such switches may not operate in the time required by specific switching applications.

' It is accordingly a general object of the invention to "provide improved multi-contact switching apparatus.

It is another object of the invention to provide multicontact switching apparatus which while handling very large currents occupies a minimum volume.

It is a further object of the invention to provide multicontact switching apparatus of the class described which is fast acting.

The invention is embodied in apparatus which comprises a movable support for two rows of contacts which are electrically connected in pairs while all the contacts in the same row are insulated from each other. A fixed support member also carries insulatively two rows of contacts that are cooperatively'disposed with the rows of contacts on the movable support member. The contacts of one row carried by the fixed support member are adapted to be coupled to one terminal of the transformer while the contacts of the other row carried by the fixed support member are divided into two groups which are adapted to be coupled respectively to two successive taps of the winding of the transformer via adequate impedances.

One feature of the invention is embodied in an electrical contact slidably mounted in a support means with spring means provided to ensure contact pressure against another electrical contact.

A further feature of the invention is incorporated in a hood which is disposed with respect to the electrical contacts for drawing off gases developed by electrical arcs created by the movement of electrical contacts.

Other objects, features and advantages of the invention will be evident from the following detailed description of the invention when read in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view, partially broken away, of a multi-contact switching means in accordance with the invention;

FIG. 2 is a schematic diagram of the electrical connections provided by the contacts of the multi-contact switching means of FIG. 1;

FIG. 3 shows one row of contacts disposed on a movable support means and the cooperating rows of contacts on a fixed support means of the multi-contact switching means of FIG. 1;

FIG. 4 is a sectional view taken along the line 44 of FIG. 3;

FIG. 5 is a side view partially in section of one of the contacts on the fixed support means as shown in FIG. 3;

FIG. 6 is a cross-sectional view of the electrical contact of FIG. 5; and

FIG. 7 is a schematic representation of a hood incorporated in the multi-contact switching means of FIG. 1.

FIG. 1, in general, shows a multi-contact switching means 10 comprising a fixed support member 12 encompassing a movable support member 14 of insulative material. Disposed in movable support member 14 are a first row of contacts 16 (a-n) and a second row of contacts 18(a-n). As is hereinafter more fully disclosed, each of the contacts 16 is respectively connected electrically to an associated contact 18 to form a pair of contacts. Disposed in fixed support member 12 are a first row of contacts 20(an) cooperative with contacts 16(a-n) and a second row of contacts 22(a-n) cooperative with contacts 18(a-n). Associated with each of the contacts 20 is a flexible cable 24 having one end fixed to the contact 20 and the other end fixed to a common conductor 26 for connection to one terminal of the transformer (not shown). Similarly, associated with each of the contacts 22 is a flexible cable 28. One end of each cable 28 is connected to its associated contact 22 and the other end is connected to a terminal 31 which is connected to a tap of the winding of the transformer via an appropriate impedance (not shown).

Movable support means 14 is coupled to a rotary drive means 32, hereinafter more fully described. As rotary drive means 32 rotates, sequential connections are made between contacts 16 and 20, and between contacts 18 and 22. As these connections are made and broken there is usually considerable electrical arcing which develops gases. To facilitate the removal of these gases a hood 34 and a chimney or conduit 36 is disposed above the contacts 22.

More particularly, FIG. 2 shows schematically the electrical connections effected by the multi-contact switching means 10. The contacts 22a and 22n which may be considered fixed contacts are shown connected respectively to two successive taps of the winding of the transformer while the other contacts of the same row 22b 22n are shown connected to the same taps via the corresponding impedances. The contacts 16(a-n) which may be considered moving contacts, are connected via jumpers 38(an) to respective contacts 18(a-n) which may also be considered in pairs, that is contact 16a via jumper 38a to contact 1812, contact 16b via jumper 38b to contact 185, etc. Thus, when movable support member 14 (FIG. 1) is rotated there are sequential connections between contacts 20 and 22, that is contact 20a to contact 22a, then contact 2011 to contact 22b, etc. There Will be two makes or breaks in series in each case to minimize the voltages developed across pairs of contacts.

FIG. 3 shows in greater detail the cooperation between the row of contacts 20(a-n) mounted in fixed support member 12 and the corresponding row of contacts 16(a-n) carried by movable support member 14. Movable support member 14 is connected via an arm 40 to a tacts 18(a-n) and the contacts 22(a-n).

in FIGS. and 6. fixed to one-end of a plunger 52. Fixed to contact point shaft 42. Shaft 42 is disposed in a hub member 44. A central shaft 46 imparts rotary motion to hub member 44. Thus, movable support member 14 is eccentrically coupled to rotary drive means 32. During the rotation of shaft 46 on rotary drive means 32 the eccentric action transmitted by shaft 42 and arm 40 causes the contacts 16 (a-n) to sequentially roll over the associated contacts 20(a-n). A similar action takes place between the con- It should be noted that this eccentric type of arrangement permits a shortening of the radius of rotation of the movable support member 14. Thus, the inertia of the system is mini- 'mized which is highly desirable in quick-action devices.

FIG. 4, which is a sectional view of FIG. 3 shows primarily the electrical connection established between contacts 20 and 22 when contacts 16 and 18 are in position against contacts 20 and 22 respectively. Imbedded in the insulating material of movable support member 14 is a jumper 38 which forms a permanent electrical connection between the contacts 16 and 18.

A more detailed view of one of the contacts 20 is shown In particular, a contact point 50 is 50 is a flexible cable 24 which couples the contact 21) to the common terminal 26. A sleeve 54 slidably accommodates plunger 52 to permit free axial movement thereof. The sleeve 54 has an axial length shorter than the axial length of the plunger 52. A collar 56 is fitted on the extending end of the plunger 52 remote from the coni l 54 prevent the escape of the ball bearings 64 and 66 I from their races.

To enhance the connection between the contacts 20 and the associated contacts 16 spring biasing means is included in the contact 20. More particularly, a torsion spring 76 is-developed about a bar 78 which is connected via support member 80 to sleeve 54. One end 82 of torsion spring 76 is hooked into a slot 84 of support member 80 while theother end 86 is engaged in a hole 88 of plunger 52. Thus, plunger 52 is urged forward in the direction of the contact point 50.

Since there are often gases formed due to the electrical arcing when electrical contacts are made and broken, and since these gases are ionized, it is highly desirable to exhaust the gases developed about the lower contacts to prevent them from reaching the upper contacts where they would cause arcing between them. Accordingly, FIG. 7 shows schematically a hood 34 for exhausting the gases. The hood 34 is disposed above the contacts 22 (a-n). A conduit 36 is coupled to a hole or exit port in the top of the hood 34 to prevent the gases developed about the contacts 22 from fouling the atmosphere about the contacts 20. In addition, partitions 90(a-n) interposed between pairs of adjacent contacts 22 prevent the gases from spreading between the contacts. It should be noted that the hood 34 and the partitions 90 are of a material that is resistant to the high temperatures associated with electrical arcs. It should be further noted that the exact dimensions of the hood 34 are dependent on the clearance between the movable support member 14 and the fixed support member 12 (see FIG. 1).

There has thus been shown improved multi-contact switching means which permits the switching of greater quantities of electrical energy without increasing the size of the switch gear. The multi-contact switching means because it employs eccentric action for driving the movable support member minimizes the inertia of the system thus permitting more rapid switching.

Further improved contacts have been shown which by using spring biasing increase the reliability of the electrical connection formed during the switching action.

There has also been shown means for preventing the parting from the spirit of the invention as defined by the appended claims.

What I claim and desire to secure by letters Patent is: 1. In an electrical switch having a plurality of fixed contacts arranged in two rows comprising an upper row and a lower row, a rotary bridge element having two rows of mobile contacts for engaging the contacts of said upper and lower rows sequentially and bridging pairs of contacts in the upper and lower rows, the improvement which comprises a hood disposed between said upper and lower rows of mobile and stationary contacts opening onto said lower rows of mobile and stationary contacts in common and having means to transport ionized gases from said lower contacts clear of the upper rows of contacts and externally of said switch, thereby to prevent said ionized gases from assisting in causing arcing at said upper rows of contacts.

2. In an 'electricalswitch according to claim 1, in which said means to transport said ionized gases comprises an upwardly extending conduit for venting said gases upwardly and outwardly of said switch.

3. In an electrical switch according to claim 2, in which said hood comprises a plurality of upwardly extending portions therein disposed spaced in planes between the contacts of said lower rows of mobile and stationary contacts.

References Cited in the file of this patent UNITED STATES PATENTS D. 23,951 Potter Jan. 8, 1895 1,398,981 Tritle Dec. 6, 1921 1,828,300 Slepian Oct. 20, 1931 2,680,163 Besserer June 1, 1954 

1. IN AN ELECTRICAL SWITCH HAVING A PLURALITY OF FIXED CONTACTS ARRANGED IN TWO ROWS COMPRISING AN UPPER ROW AND A LOWER ROW, A ROTARY BRIDGE ELEMENT HAVING TWO ROWS OF MOBILE CONTACTS FOR ENGAGING THE CONTACTS OF SAID UPPER AND LOWER ROWS SEQUENTIALLY AND BRIDGING PAIRS OF CONTACTS IN THE UPPER AND LOWER ROWS, THE IMPROVEMENT WHICH COMPRISES A HOOD DISPOSED BETWEEN SAID UPPER AND LOWER ROWS OF MOBILE AND STATIONARY CONTACTS OPENING ONTO SAID LOWER ROWS OF MOBILE AND STATIONARY CONTACTS IN COMMON AND HAVING MEANS TO TRANSPORT IONIZED GASES FROM SAID LOWER CONTACTS CLEAR OF THE UPPER ROWS OF CONTACTS AND EXTERNALLY OF SAID SWITCH, THEREBY TO PREVENT SAID IONIZED GASES FROM ASSISTING IN CAUSING ARCING AT SAID UPPER ROWS OF CONTACTS. 